Vincent du Vigneaud began experimenting with explosives in his spare time while he was still in high school, and worked his way through college with jobs as an apple picker, librarian's assistant, mechanic, and waiter. He studied the hormone insulin, methyl groups, and penicillin, and researched sulfur compounds, particularly the amino acids cystine, cysteine, and methionine, each of which contain sulfur. He isolated vitamin H (biotin) in 1940, and described its structure in 1942. He synthesized penicillin in 1946, synthesized the pituitary hormones oxytocin and vasopressin in 1953 and 1954, respectively, and won the Nobel Prize for Chemistry in 1955. He was idled by a stroke in 1974, and died four years later. He was known for his general joviality, and friends called him "Dee".